Nearly 15 million US homeowners struggle to optimally control the quality of the water in their pools. (As used herein, “pools” includes spas.) The water is affected by environmental factors such as sunlight, wind, pollen, debris, rain and human factors such as skin bacteria, sweat and urine. Most homeowners or their hired pool service make adjustments on a weekly basis at best. In order to deal with changing conditions, most users overdose their pools with circulating disinfectants, resulting in harsh water that attacks skin, hair and bathing suits, and often requiring additional chemicals to maintain pH. Water chemistry parameters are mutually dependent where free chlorine (“FC”) requires a narrow pH range in order to effectively oxidize organic matter and purify the water. If not enough effective disinfectant is present, nutrients in the pool can cause an algae bloom requiring further expensive chemicals and environmentally damaging water change often in excess of 15,000 gallons. This results in over $2.6 billion spent each year in the US by consumers on pool chemicals such as disinfectants, water balance adjusters (for pH, total alkalinity, calcium hardness, and cyanuric acid), algaecides, clarifiers, flocculants, and enzymes which need to be manually administered to pools. Since the popularization of back yard pools in over 15% of all households, no automatic, easy to deploy, cost effective systems have been commercially available to address these needs.
According to the US Department of Energy, the average pool requires 1,500 kWh per year in order to operate its filtration and circulation pumps. Many pool pumps run on a timer that is not responsive to actual filtration need. Saltwater chlorine generators also require significant power and maintenance and are also run on a timer that is not responsive to the actual need of disinfectant in the pools.
Nearly 90% of pool owners in the US maintain their own pools and spas and are not able or willing to make significant investment in installing new equipment requiring plumbing or electrical connections.
Several partial solutions have been offered to the consumer. Manual colorimetric test strips exist that indicate the state of chemicals in the pool water, but those must be applied manually, read on multi-colored comparison charts, and translated to the correct balancing mixture of chemicals needed. It is difficult for the user to connect these weekly measurements and compute the dynamic trajectory of pool water and the required corrective action. This results in over or under correction both of which can be very expensive.
There exist some automation systems for the residential pool market (e.g., the Hayward Sense and Dispense® system). These systems are costly to install and costly to maintain. In addition, they require a disruption of existing plumbing. These systems control only for chlorine and pH and have oxidation-reduction potential (ORP) sensors with a sensitive platinum electrode and pH sensors with a sensitive glass bulb, both of which need regular maintenance for calibration and cleaning.
Dosing disinfectant using tricholoroisocyanuric acid (“trichlor”) pucks eluting chlorine from a floating dispenser are the most common. Most users do not bother to manually adjust the dispensing rate in response to pool chlorine demand, however. An inline chlorinator/feeder also uses trichlor pucks, but its dispensing rate is also rarely manually adjusted. Both trichlor dispensing systems require users to handle a hazardous chemical oxidizing puck when these dispensers have to be replenished. Saltwater chlorine generators work on timers that also are rarely manually adjusted based on chlorine demand.
Balancing the pH, alkalinity, and calcium levels of the pool water requires additional measurements, calculations and manual administration of chemicals.
It should be further appreciated that all the processes affecting pool water chemistry mentioned above are not linear, yet users routinely attempt to control them with step adjustments such as adding a fixed amount of chemicals, or changing the setting on a chlorine dispenser, pump timer, etc. subject to infrequent measurement, typically once per week at best. This approach inevitably results in suboptimal adjustments. The present invention describes a modular battery operated system that may be easily deployed one module at a time to deal with the tedious aspects of pool maintenance and relieves the user from these manual tasks and makes repeated measurements and optimized dynamic dosing to keep pool water in ideal condition.
It should be further appreciated that pool service personnel currently use fixed schedules and routes resulting in either visiting pools on their route too frequently or too infrequently often involving considerable driving time and expense. The present invention automatically takes care of most maintenance issues, advises the service center of pool conditions and often proactively reports service issues before they become problems, thereby allowing pool service personnel to perform their work more efficiently by minimizing truck rolls and optimizing routing based on actual service need.
It should be further appreciated that any man-made body of water may require chemical monitoring and adjustment. Cooling towers have to be routinely maintained with sanitizer to avoid bacteria growth that can lead to Legionnaires' disease. In addition to cooling towers, hot tubs, fountains, koi ponds, containment ponds and other open or closed water systems could benefit from one or more of the modules described herein each of which is of low cost, requiring no complex calibration or cleaning, and all but one (the pump control module) are easily added to the pool by the pool owner without need for professional installation.
Colorimetric strips (e.g., Hach Aquachek®, ITS Sensafe®, LaMotte Insta-TEST®) have been available for decades and are the most popular means for analyzing the key analytes in pool water such as FC, pH, alkalinity, and hardness. These pad strips must be manually dipped in the water and the color of the pads compared to a standard chart to read the analyte level. The pad strips must be kept in a sealed container so they do not degrade due to exposure to moisture in the form of liquid water or water vapor present in humid air.
Electronic probes for measuring pH and ORP (which is related to, but not a direct measurement of FC) have been available in commercial systems, but these probes are prone to degradation and calibration drift. While some of these systems simply provide open loop monitoring, others control the dispensing of chemicals based on monitored parameters, such as in U.S. Pat. No. 8,797,523.
Automated pool chemical sensing technology suffers from certain drawbacks. For example, systems have been proposed to sequentially expose pads to pool water as described in U.S. Pat. Nos. 6,113,858 and 8,197,755 or as demonstrated by the Blue I Water Technologies PRIZMA® system (http://www.blueitechnologies.com/products/prizma/), but they do not provide for a way to prevent moisture degradation to the analyte pads or the ability to keep them in the pool water prior to use.
In addition to water chemical monitoring, turbidity monitors have been used to control water circulation pumps in pools, such as described in US Publ. No. 2011/0253638. Circulating water pumps have also been controlled based on pool usage, as described in U.S. Pat. No. 5,804,080.